Performance optimizations for memory footprint and startup time
Linux on x86-64
Linux on ppc64le
Linux on 390x
This is a source code only project, containing a portion of the overall function needed to provide a full Java Developer's Kit (JDK) implementation. To run Java applications, OpenJ9 must be combined with the non-JVM parts of a JDK, such as OpenJDK.
Eclipse OpenJ9 supports and will continue to support multiple JDK levels from the same source code. Although OpenJ9 is compatible with JDK8, this release does not bring full compliance. We expect to include JDK8 and JDK9 compliance in the next release.
The Eclipse OpenJ9 project builds on top of the Eclipse OMR project code. OMR has not yet produced an official release, but we have found the project to be suffiently stable that the OpenJ9 community are willing to produce this OpenJ9 release using a particular commit from OMR and will support that code ourselves (contributing relevant fixes back to OMR). We will be relaxing this coupling over time by working with the Eclipse OMR community.
All testing has been run against a compiled version of this component, both in isolation and when combined with OpenJDK to provide a full Java implemention.
Some user documentation is available on the Eclipse OpenJ9 web site (https://www.eclipse.org/openj9/), covering aspects such as how to build OpenJDK binaries that includes the OpenJ9 VM on multiple platforms, plus frequently asked questions.
User documentation to customise or tune Eclipse OpenJ9 is not yet contributed to the project. This work is underway. As an interim measure, users can access the J9 VM reference (https://www.ibm.com/support/knowledgecenter/en/SSYKE2_9.0.0/j9vm_reference.html)
in the IBM Knowledge Center, which forms part of the IBM SDK, Java Technology Edition documentation. This information is up to date and applicable when using Eclipse OpenJ9 in almost all cases.
Conforms To UI/UX Guidelines:
Not applicable (project doesn't provide UI)
The project has been mostly using GitHub issues at the main repository (eclipse/openj9) to handle the work of the project and communicate with our community. In particular, we have not been actively using the dev list at this point. We regularly monitor Stack Overflow for OpenJ9 related questions. We respond promptly when newcomers open issues and have addressed a number of issues affecting performance as well as functionality. Recently, we created a slack channel for all users, adopters, and contributors/committers to be able to reach out to our community, and added a signup button to our main web page. We have written a small number of articles and several committers have delivered talks at conferences like Java One, QCON SF, CASCON, and we already have several talks scheduled at development conferences in early 2018 to continue to get the word out.